Grafting-modified cyclic polymer, process for producing the same, and curable composition

ABSTRACT

A graft polymer containing a cyclic structure comprised of a polymer containing a cyclic structure graft-modified with an unsaturated compound containing a polar group, having a graft ratio of 10 to 150 mol %, having a weight average molecular weight of 1,000 to 1,000,000, and having a gel content of not more than 0.1 wt % or having a ratio (Ha/La) of high molecular weight side area (Ha) and low molecular weight side area (La) divided by a vertical line suspended from a peak top of a differentiated elution profile measured by gel permeation chromatography to a baseline of not more than 1.6, a method of production of the same, and a curable composition containing that graft polymer containing a cyclic structure and a curing agent.

TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates to a graft polymer containing acyclic structure, a method of production of the same, and a curablecomposition containing that graft polymer. More particularly, it relatesto a graft polymer containing a cyclic structure having a high graftratio, having a good filterability of solution when dissolved in asolvent, superior in surface hardness of a coating obtained by coatingthat solution, superior in smoothness and flatness of a coating on amicro-circuit board, and having a good heat resistance, a method ofproduction of the same, and a curable composition containing that graftpolymer.

BACKGROUND ART

[0002] Along with the increasingly smaller sizes and greater number offunctions of electronic equipment, greater density of the circuit boardsused in the electronic equipment is also being sought. The generalmethod for increasing the density of circuit boards is to make theinterconnections finer, that is, reduce the line widths. As insulationmaterials used for this purpose, curable compositions superior in lowdielectric property, low water absorption, and heat resistance are beingsought. For example, International Publication WO98/56011 discloses thefollowing curable composition. This curable composition is obtained byfiltering a graft polymer containing a cyclic structure by a filter of apore size of 0.22 μm, then dissolving or dispersing it in an organicsolvent together with a curing agent. The graft polymer containing acyclic structure is produced by graft modifying a norbornene-basedpolymer or other polymer containing a cyclic structure in xylene oranother hydrocarbon-based solvent in the presence of a large amount ofperoxide by maleic anhydride or another unsaturated compound by 25 mol%.

[0003] On the other hand, in applications of electronic equipment, therehas been a sharp increase in fields where a high heat resistance issought in the insulating materials as well and fields where surfacehardness for multilayer structures are sought. To deal with this, in thecurable composition described in the above international publication, agraft polymer containing a cyclic structure having a high graft ratiohas to be used. The graft polymer containing a cyclic structure of thehigh graft ratio described in that international publication improvesthe heat resistance and the surface hardness, but has a large gelcontent, so the solution of the polymer dissolved in a solvent cannot befiltered. Therefore, the coating film has the defects of insufficientsmoothness and flatness.

DISCLOSURE OF INVENTION

[0004] An object of the present invention is to provide a graft polymercontaining a cyclic structure having a high graft ratio, having a goodfilterability of solution when dissolved in a solvent, and giving acoating film when coating the solution which is good in smoothness,flatness, surface hardness, etc. and superior in low dielectricproperty, low water absorption, and heat resistance.

[0005] Another object of the present invention is to provide a method ofproduction of this graft polymer containing a cyclic structure.

[0006] A still other object of the present invention is to provide acurable composition including this graft polymer containing a cyclicstructure.

[0007] The present inventors discovered that a coating film obtained bycuring by a curing agent a graft polymer containing a cyclic structurehaving a high graft ratio and low gel content or small high molecularweight ingredients can be improved in the surface hardness or heatresistance without impairing the low dielectric rate or low waterabsorption and when formed on a micro-circuit board is superior insmoothness and flatness as well.

[0008] Further, the present inventors discovered that by using as areaction solvent a mixed solvent of a nonpolar organic solvent and polarorganic solvent, a graft polymer containing a cyclic structure havingthe above characteristics can be easily obtained and further that ifgradually adding a peroxide, production of high molecular weightingredients can be more effectively suppressed.

[0009] Further, the present inventors discovered that if employing themethod of production comprising dissolving the polymer containing acyclic structure in an organic solvent and in that state graduallyadding a peroxide and unsaturated organic compound containing a polargroup, the graft polymer containing a cyclic structure obtained will notbe colored much and little agglomerates will be formed.

[0010] The present invention was perfected based on these discoveries.

[0011] According to the present invention, there is provided a graftpolymer containing a cyclic structure comprised of a polymer containinga cyclic structure graft-modified with an unsaturated compoundcontaining a polar group, having a graft ratio of 10 to 150 mol %,having a gel content of not more than 0.1 wt %, and having a weightaverage molecular weight (Mw) of 1,000 to 1,000,000.

[0012] Further, according to the present invention, there is provided agraft polymer containing a cyclic structure comprised of a polymercontaining a cyclic structure graft-modified with an unsaturatedcompound containing a polar group, having a graft ratio of 10 to 150 mol%, having a ratio (Ha/La) of a high molecular weight side area (Ha) anda low molecular weight side area (La) divided by a vertical linesuspended from a peak top of a differentiated elution profile measuredby gel permeation chromatography to a baseline of not more than 1.6, andhaving an Mw of 1,000 to 1,000,000.

[0013] Further, according to the present invention, there is provided amethod of production of a graft polymer containing a cyclic structurecomprising dissolving a polymer containing a cyclic structure andunsaturated compound containing a polar group in a mixed solvent of anonpolar organic solvent and a polar organic solvent and in that statecausing a graft reaction of the unsaturated compound containing a polargroup with the polymer containing a cyclic structure in the presence ofa peroxide.

[0014] Further, according to the present invention, there is provided amethod of production of a graft polymer containing a cyclic structurecomprising dissolving a polymer containing a cyclic structure andunsaturated compound containing a polar group in a mixed solvent of anonpolar organic solvent and a polar organic solvent and in that statecausing a graft reaction of the unsaturated compound containing a polargroup while continuously or intermittently adding a peroxide.

[0015] Further, according to the present invention, there is provided amethod of production of a graft polymer containing a cyclic structurecomprising dissolving a polymer containing a cyclic structure in anorganic solvent and in that state causing a graft reaction of anunsaturated compound containing a polar group with the polymercontaining a cyclic structure while continuously or intermittentlyadding a peroxide and the unsaturated compound containing a polar group.

[0016] Further, according to the present invention, there is provided acurable composition containing the above graft polymer containing acyclic structure and a curing agent.

[0017] The curable composition containing the graft polymer containing acyclic structure of the present invention is good in filterability andgives a coating film superior in smoothness, flatness, surface hardness,etc. and good in low dielectric property, low water absorption, and heatresistance. Therefore, in the form of a film or sheet, it is used for aninsulating material for a printed writing board, an insulating materialfilm between layers for a semiconductor device, a protective coatingmaterial for a semiconductor device, a solder resist material for aprinted writing board, a color filter for a liquid crystal displaysubstrate, a flattening film for various interconnections, cells for aliquid crystal display, etc.

BEST MODE FOR CARRYING OUT THE INVENTION

[0018] Graft Polymer Containing a Cyclic Structure

[0019] The graft polymer containing a cyclic structure of the presentinvention is comprised of a polymer containing a cyclic structuregraft-modified by an unsaturated compound containing a polar group andis characterized by a high graft ratio and low gel content.

[0020] (A) Polymer Containing a Cyclic Structure

[0021] A polymer containing a cyclic structure is a homopolymer or acopolymer having repeating units having a cyclic structure at its mainchain and/or side chain. From the viewpoint of the heat resistance,solvent resistance, etc., it preferably contains a cyclic structure atits main chain. As the cyclic structure, for example, an aromatic cyclicstructure, saturated cyclic hydrocarbon (cycloalkane) structure,unsaturated cyclic hydrocarbon (cycloalkene) structure, etc. may bementioned, but from the viewpoint of the low dielectric property, lowwater absorption, transparency, heat resistance, and surface hardness, acycloalkane structure is preferable. Further, as a cyclic structure, amonocyclic or polycyclic structure (condensation polycyclic structure,cross-linking cyclic structure, combination polycyclic structures of thesame, etc.) may be mentioned. The number of carbon atoms forming thecyclic structure is not particularly limited, but usually is 4 to 30,preferably 5 to 20, more preferably 5 to 15. If in this range, thevarious properties of the heat resistance, surface hardness, andshapeability are balanced to a high degree and suitable.

[0022] The ratio of the repeating units containing cyclic structures inthe polymer containing a cyclic structure is suitably selected inaccordance with the object of use, but normally is 30 to 100 wt %,preferably 50 to 100 wt %, more preferably 70 to 100 wt %. If the ratioof the repeating units containing cyclic structures in the polymercontaining a cyclic structure is excessively small, the polymer is poorin dielectric property, water absorption, heat resistance, and surfacehardness and therefore not preferable. The rest of the polymercontaining a cyclic structure other than the repeating units containingcyclic structures is not particularly limited and may be suitablyselected in accordance with the object of use.

[0023] As specific examples of the polymer having a cyclic structure,(1) a norbornene-based polymer, (2) monocyclic olefin-based polymer, (3)cyclic conjugated diene-based polymer, (4) vinyl-based cyclichydrocarbon-based polymer, (5) aromatic polymer having repeating unitsof aromatic rings in its main chain, (6) hydrides of the same, etc. maybe mentioned. Among these, a norbornene-based polymer and its hydrides,cyclic conjugated diene-based polymer and its hydrides, etc. arepreferable. A norbornene-based polymer and its hydrides are particularlypreferable.

[0024] (1) Norbornene-Based Polymer

[0025] The norbornene-based polymer is not particularly limited. Forexample, ones obtaining by polymerizing norbornene-based monomers by themethod disclosed in Japanese Unexamined Patent Publication (Kokai) No.3-14882, Japanese Unexamined Patent Publication (Kokai) No. 3-122137,etc. may be mentioned. Specifically, ring-opening polymers ofnorbornene-based monomers and their hydrides, addition polymers ofnorbornene-based monomers, addition copolymers of norbornene-basedmonomers and vinyl compounds, etc. may be mentioned. Among these, fromthe viewpoint of obtaining a graft unsaturated organic compound having ahigh graft ratio and low gel content, a ring-opening polymer hydride ofa norbornene-based monomer, an addition polymer of a norbornene-basedmonomer, or an addition copolymer of a norbornene-based monomer andcopolymerizable vinyl compound is preferable. A ring-opening polymerhydride of a norbornene-based monomer is particularly preferable.

[0026] As specific examples of the norbornene-based monomer,bicyclo[2,2,1]-hept-2-ene (common name: norbornene),5-methyl-bicyclo[2,2,1]-hept-2-ene,5,5-dimethyl-bicyclo[2,2,1]-hept-2-ene,5-ethyl-bicyclo[2,2,1]-hept-2-ene, 5-butyl-bicyclo[2,2,1]-hept-2-ene,5-hexyl-bicyclo[2,2,1]-hept-2-ene, 5-octyl-bicyclo[2,2,1]-hept-2-ene,5-octadecyl-bicyclo[2,2,1]-hept-2-ene,5-ethylidene-bicyclo[2,2,1]-hept-2-ene,5-methylidene-bicyclo[2,2,1]-hept-2-ene,5-vinyl-bicyclo[2,2,1]-hept-2-ene, 5-propenyl-bicyclo[2,2,1]-hept-2-ene,tricyclo[4,3,0,1^(2,5)]-deca-3,7-diene (common name“dicyclopentadiene”), tricyclo[4,4,0,1^(2,5)]-undeca-3,8-di ene,tricyclo[4,4,0,1^(2,5)]-undec-3-ene,5-cyclopentyl-bicyclo[2,2,1]-hept-2-ene,5-cyclohexyl-bicyclo[2,2,1]-hept-2-ene,5-cyclohexenyl-bicyclo[2,2,1]-hept-2-ene, 5-phenyl-bicyclo[2,2,1]-hept-2-ene, tetracyclo[4,4,0,1^(2,5),1^(7,10)]-dodeca-3-ene (sometimessimply called “tetracyclododecene),8-methyl-tetracyclo[4,4,0,1^(2,5),1^(7,10)]-dodeca-3-ene,8-ethyl-tetracyclo[4,4,0,1^(2,5),1^(7,10)]-dodeca-3-ene,8-methylidene-tetracyclo[4,4,0,1^(2,5),1^(7,10)]-dodeca-3-ene,8-ethylidene-tetracyclo[4,4,0,1^(2,5),1^(7,10)]-dodeca-3-ene,8-vinyl-tetracyclo[4,4,0,1^(2,5),1^(7,10)]-dodeca-3-ene,8-propenyl-tetracyclo[4,4,0,1^(2,5),1^(7,10)]-dodeca-3-ene,8-cyclopentyl-tetracyclo[4,4,0,1^(2,5),1^(7,10)]-dodeca-3-ene,8-cyclohexyl-tetracyclo[4,4,0,1^(2,5),1^(7,10)]-dodeca-3-ene,8-cyclohexenyl-tetracyclo[4,4,0,1^(2,5),1^(7,10)]-dodeca-3-ene,8-phenyl-cyclopentyl-tetracyclo[4,4,0,1^(2,5),1^(7,10)]-dodeca-3-ene;

[0027] tetracyclo[7,4,0,1^(10,13),0^(2,7)]trideca-2,4,6,11-tetraene(also called “1,4-methano-1,4,4a,9a-tetrahydrofluorene”),tetracyclo[8,4,0,1^(11,14),0^(3,8)] trideca-3,5,7,12-tetraene (alsocalled “1,4-methano-1,4,4a,5,10,10a-hex ahydroanthracene”),pentacyclo[6,5,1^(3,6),0^(2,7),0^(9,13)] pentad eca-3,10-diene;pentacyclo[7,4,0,1^(3,6),1^(10,13),0^(2,7)]pentadec a-4,11-diene,addition products of at least tetramers of cyclopentadiene,5-phenylbicyclo[2,2,1]-hept-2-ene, tetracyclo[6,5,0,1^(2,5)0^(8,13)]trideca-3,8,10,12-tetraene (also called“1,4-methano-1,4,4a,9a-tetrahydrofluoren” ),tetracyclo[6,6,0,1^(2,5),0^(8,13)]tetradeca-3,8,10,12-tetrae ne (alsocalled “1,4-methano-1,4,4a,5,10,10a-hexahydro anthracene”), and othernorbornene-based monomers not having a polar group;

[0028] 5-methoxycarbonyl-bicyclo[2,2,1]-hept-2-ene,5-methyl-5-methoxycarbonyl-bicyclo[2,2,1]-hept-2-ene,5-ethoxycarbonyl-bicyclo[2,2,1]-hept-2-ene,5-methyl-5-ethoxycarbonyl-bicyclo[2,2,1]-hept-2-ene,bicyclo[2,2,1]-hept-5-enyl-2-methylpropionate,bicyclo[2,2,1]-hept-5-enyl-2-methyloctanate,bicyclo[2,2,1]-hept-2-en-5,6-dicarboxylic anhydride,5-hydroxymethyl-bicyclo[2,2,1]-hept-2-ene,5,6-di(hydroxymethyl)bicyclo[2,2,1]-hept-2-ene,5-hydroxy-i-propyl-bicyclo[2,2,1]-hept-2-ene,5,6-dicarboxy-bicyclo[2,2,1]-hept-2-ene;5-cyanobicyclo[2,2,1]-hept-2-ene,bicyclo[2,2,1]-hept-2-en-5,6-dicarboxylate imide,8-methoxycarbonyl-tetracyclo[4,4,0,1^(2,5),1^(7,10)]-dod eca-3-ene,8-methyl-8-methoxycarbonyl-tetracyclo[4,4,0,1^(2,5),1^(7,10)]-dodeca-3-ene,8-hydroxymethyl-tetracyclo[4,4,0,1^(2,5),1^(7,10)]-dodeca-3-ene,8-carboxy-tetracyclo[4,4,0,1^(2,5),1^(7,10)]-dodeca-3-ene, and othernorbornene-based monomers having polar groups etc. may be mentioned.Among these norbornene-based monomers, norbornene-based monomers nothaving polar groups are suitable since the polymers obtained using thesame give a superior low dielectric property, low water absorption, andtransparency.

[0029] These norbornene-based monomers may be used alone or incombinations of two or more types. The norbornene-based polymer may alsobe a copolymer between a norbornene-based monomer and another monomerable to be copolymerized with this (hereinafter called a “comonomer”).The ratio of the norbornene-based monomer bonds in the norbornene-basedpolymer is suitably selected in accordance with the object of use, butnormally is at least 30 wt %, preferably at least 50%, more preferablyat least 70 wt %. Such a one is very well balanced in low dielectricproperty, low water absorption, heat resistance, and surface hardness.

[0030] As comonomers of the above norbornene-based monomers, ethylene,propylene, 1-butene, 1-pentene, 1-hexene, 3-methyl-1-butene,3-methyl-1-pentene, 3-ethyl-1-pentene, 4-methyl-1-pentene,4-methyl-1-hexene, 4,4-dimethyl-1-hexene, 4,4-dimethyl-1-pentene,4-ethyl-1-hexene, 3-ethyl-1-hexene, 1-octene, 1-decene, 1-dodecene,1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicocene, and other C₂ toC₂₀ ethylenes or α-olefins; cyclobutene, cyclopentene, cyclohexene,3,4-dimethylcyclopentene, 3-methylcyclohexene,2-(2-methylbutyl)-1-cyclohexene, cyclooctene,3a,5,6,7a-tetrahydro-4,7-methano-1H-indene, and other cycloolefins;1,4-hexadiene, 4-methyl-1,4-hexadiene, 5-methyl-1,4-hexadiene,1,7-octadiene, and other unconjugated dienes, etc. may be mentioned.These may be used alone or in combinations of two or more types.

[0031] The method of polymerization and method of hydrogenation of thenorbornene-based monomer or norbornene-based monomer and comonomer arenot particularly limited. Known methods may be followed.

[0032] A ring-opening (co)polymer of a norbornene-based monomer can beobtained using as the ring-opening polymerization catalyst a catalystsystem comprised of a halide, nitrate, or acetylacetone compound of ametal such as ruthenium, rhodium, palladium, osmium, iridium, andplatinum or a catalyst system comprised of a halide or acetylacetonecompound of a metal such as titanium, vanadium, zirconium, tungsten, andmolybdenum and an organoaluminum compound in a solvent or not in asolvent to cause ring-opening (co)polymerization normally at apolymerization temperature of −50° C. to 100° C. and a polymerizationpressure of 0 to 50 kg/cm². It is possible to add to the catalyst systemmolecular oxygen, an alcohol, ether, peroxide, carboxylic acid, acidanhydride, acid chloride, ester, ketone, nitrogen-containing compound,sulfur-containing compound, halogen-containing compound, moleculariodine, and other Lewis acids and other tertiary ingredients to raisethe polymerization activity and the ring-opening polymerizationselectivity.

[0033] An addition type copolymer of a norbornene-based monomer andcopolymer can for example be obtained by the method of for examplecopolymerizing the monomer ingredients in a solvent or not in a solventin the presence of a catalyst system comprised of a vanadium compoundand an organoaluminum compound normally at a polymerization temperatureof −50° C. to 100° C. and a polymerization pressure of 0 to 50 kg/cm².

[0034] A hydrogenated norbornene-based polymer may be obtained by themethod of hydrogenating a ring-opening (co)polymer by an ordinary methodby hydrogen in the presence of a hydrogenation catalyst. Due to thehydrogenation, the carbon-carbon unsaturated bonds present in the mainchain or side chain are partially or fully hydrogenated and saturated.In the case of a norbornene-based polymer containing an aromatic ring,the aromatic ring may be hydrogenated by hydrogenation or only thenon-aromatic carbon-carbon unsaturated bonds of the main chain and sidechain may be selectively hydrogenated.

[0035] (2) Monocyclic Olefin-Based Polymer

[0036] As the monocyclic olefin-based polymer, for example, the onesdisclosed in Japanese Unexamined Patent Publication (Kokai) No.64-66216, that is, addition homo polymers or copolymers of cyclohexene,cycloheptene, cyclooctene, and other monocyclic olefin-based monomers orcopolymers of these mono cyclic olefin-based monomers and similarcomonomers as the case of said norbornene-based monomer polymers may beused.

[0037] (3) Cyclic Conjugated Diene-Based Polymer

[0038] As the cyclic conjugated diene-based polymer, for example, theones disclosed in Japanese Unexamined Patent Publication (Kokai) No.6-136057 or Japanese Unexamined Patent Publication (Kokai) No. 7-258318,that is, (co)polymers obtained by 1,2- or 1,4-addition polymerization ofcyclopentadiene, cyclohexadiene, and other cyclic conjugated diene-basedmonomers and hydrides of the same etc. may be used.

[0039] (4) Vinyl-Based Cyclic Hydrocarbon-Based Polymer

[0040] As the vinyl-based cyclic hydrocarbon-based polymer, for example,the ones disclosed in Japanese Unexamined Patent Publication (Kokai) No.51-59989, that is homo polymers or copolymers of vinylcyclohexene,vinylcyclohexane, and other vinyl-based cyclic hydrocarbon-basedmonomers or hydrides of the same may be used. Said copolymers includecopolymers of vinylcyclohexene or vinylcyclohexane and comonomerssimilar to the case of the above norbornene-based monomer polymers.Further, those disclosed in Japanese Unexamined Patent Publication(Kokai) No. 63-43910, Japanese Unexamined Patent Publication (Kokai) No.64-1706, etc., that is, styrene, α-methylstyrene, or other vinylaromatic monomers or copolymers of vinyl aromatic monomers and monomersable to be copolymerized by the same or hydrides of the same etc. may beused.

[0041] (5) Aromatic Polymer Having Repeating Units of Aromatic Rings atMain Chain

[0042] As an aromatic polymer having repeating units of aromatic ringsin its main chain, for example, polyphenylene sulfide, polyphenyleneether, polyether sulfone, polysulfone, etc. may be used.

[0043] (B) Unsaturated Organic Compound Containing Polar Group

[0044] The unsaturated compound containing a polar group is notparticularly limited so long as it is an organic compound containing apolar group and containing radical reactive carbon-carbon unsaturatedbonds.

[0045] As the polar group, for example, a hetero atom or an atomic grouphaving a hetero atom may be mentioned. As a hetero atom, for example, anoxygen atom, nitrogen atom, sulfur atom, silicon atom, halogen atom,etc. may be mentioned, but from the viewpoint of the low dielectricproperty, low water absorption, and transparency, an oxygen atom andnitrogen atom are preferable. As specific examples of the polar group,an epoxy group, carboxyl group, hydroxyl group, oxy group, ester group,carbonyloxycarbonyl group, silanol group, silyl group, amino group,nitrile group, sulfone group, etc. may be mentioned. Among these, interms of the low dielectric property, low water absorption,transparency, and graft ratio, an epoxy group, hydroxyl group, estergroup, silanol group, carbonyloxycarbonyl group, etc. are preferable, anepoxy group and carbonyloxycarbonyl group are more preferable, and acarbonyloxycarbonyl group is particularly preferable.

[0046] As the carbon-carbon unsaturated compound containing a polargroup, glycidyl acrylate, glycidyl methacrylate,endo-cis-bicyclo[2,2,1]-hept-5-ene-2,3-d icarboxylic acid,endo-cis-bicyclo[2,2,1]-hept-5-ene-2-methyl-2,3-dicarboxylic acid, allylglycidyl ether, 2-methyl allyl glycidyl ether, a glycidyl ether ofo-allyl phenol, a glycidyl ether of m-allyl phenol, a glycidyl ether ofp-allyl phenol, and other unsaturated epoxy compounds; acrylic acid,methacrylic acid, α-ethylacrylic acid, maleic acid, fumaric acid,itaconic acid, endocis-bicyclo[2,2,1]-hept-5-ene-2,3-d icarboxylic acid,methyl-endocis-bicyclo[2,2,1]-hept-5-end-2,3-dicarboxylic acid, andother unsaturated carboxylic acid compounds; maleic anhydride,chloromaleic anhydride, butenyl succinic anhydride, tetrahydrophthalicanhydride, citraconic anhydride, and other unsaturated carboxylicanhydride compounds;

[0047] monomethyl maleate, dimethyl maleate, glycidyl maleate, and otherunsaturated ester compounds; allyl alcohol, 2-allyl-6-methoxyphenol,4-allyloxy-2-hydroxybenzophenone, 3-allyloxy-1,2-propanediol,2-allylphenol, 3-buten-1-ol, 4-penten-1-ol, 5-hexen-1-ol, and otherunsaturated alcohol compounds; chlorodimethylvinylsilane,trimethylsilylacetylene, 5-trimethylsilyl-1,3-cyclopentadiene,3-trimethylsilylallyl alcohol, trimethylsilyl methacrylate,1-trimethylsiloxy-1,3-butadiene, 1-trimethylsiloxy-cyclopentene,2-trimethylsiloxyethyl methacrylate, 2-trimethylsiloxyfuran,2-trimethylsiloxypropene, allyloxy-t-butyldimethylsilane,allyloxytrimethylsilane, and other unsaturated silane compounds etc. maybe mentioned. Among these, unsaturated epoxy compounds or unsaturatedcarboxylic anhydride compounds are preferable. In particular,unsaturated carboxylic anhydride compounds are preferable.

[0048] (C) Graft Polymer Containing a Cyclic Structure

[0049] The graft ratio x of the graft polymer containing a cyclicstructure of the present invention (if 1, meaning 100 mol %) iscalculated by the following formula based on ¹H-NMR measurement:

(D−x)/(C−x)=B/A

[0050] where, A is the sum of the peak areas of the hydrogen derivedfrom the unsaturated compound containing a polar group and B is the sumof the peak areas of the hydrogen derived from the polymer containing acyclic structure in the graft polymer containing a cyclic structure.

[0051] C is the number of hydrogen atoms in one molecule of the modifiedcompound when the unsaturated compound having a polar group is modifiedwith the polymer and, for example, for maleic anhydride, is 3.

[0052] D is the number of hydrogen atoms of one unit of the structuralmonomer of the polymer containing a cyclic structure and, in the case ofa polymer obtained by ring-opening polymerization and hydrogenation ofethyl tetracyclododecene, is 22. In the case of a copolymer, this iscalculated as the weighted average for the structural monomers.

[0053] The graft ratio is, based on the total number of monomer units inthe polymer, not lower than 10 mol %, preferably 30 mol %, morepreferably 40 mol %. On the other hand, it is not more than 150 mol %,preferably 120 mol %, more preferably 100 mol %. If the graft ratio isexcessively low, the graft polymer containing a cyclic structure fallsin heat resistance or surface hardness or becomes low in polarity andpoorer in dispersion of the curing agent, so is liable to become poor inlow water absorption, low dielectric property, and transparency.Conversely, if excessively high, it tends to deteriorate in the lowdielectric property and low water absorption.

[0054] The molecular weight of the graft polymer containing a cyclicstructure of the present invention is, in terms of the weight averagemolecular weight (Mw) converted to polystyrene measured by gelpermeation chromatography (GPC) using toluene or tetrahydrofuran (THF)as a solvent, 1,000 to 1,000,000, preferably 5,000 to 500,000, morepreferably 10,000 to 250,000. If the Mw of the graft polymer containinga cyclic structure is excessively small, the polymer is inferior insolvent resistance or heat resistance, while conversely if excessivelylarge, is inferior in dispersion of the curing agent and tends to fallin each of the characteristics of the low dielectric property, low waterabsorption, transparency, heat resistance, solvent resistance, andsurface hardness.

[0055] The ratio (Ha/La) of the high molecular weight side area (Ha) andlow molecular weight side area (La) divided by a vertical line suspendedfrom a peak top of a differentiated elution profile measured by GPCusing toluene or THF as a solvent to a baseline is normally not morethan 1.6, preferably not more than 1.4, with respect to the graftpolymer containing a cyclic structure of the present invention. If thevalue of Ha/La is in this range, the coating film is superior insmoothness, flatness, interconnection buriability, and other propertiesand therefore is preferable.

[0056] The gel content of the graft polymer containing a cyclicstructure of the present invention is obtained by filtering a 10 wt %THF solution by a Teflon filter of a pore size of 0.22 μm, thenrecovering the undissolved polymer remaining on the filter, vacuumdrying it at a temperature of 120° C. for 12 hours, then measuring theweight, and is expressed as a ratio (wt %) in the weight of the graftpolymer containing a cyclic structure before filtration. In the graftpolymer containing a cyclic structure, the value of the gel content isnot more than 0.1 wt %, preferably not more than 0.05 wt %, morepreferably not more than 0.01 wt %. If the gel content of the graftpolymer containing a cyclic structure is excessively high, the removalof the gel by the filter is difficult and the coating film prepared bythe obtained curable composition is inferior in flatness and smoothness,so this is not preferable.

[0057] (D) Graft Reaction

[0058] The first method for obtaining the graft polymer containing acyclic structure of the present invention is to dissolve the polymercontaining a cyclic structure and unsaturated compound containing apolar group in a mixed solvent of a nonpolar organic solvent and polarorganic solvent and cause a graft reaction of the unsaturated compoundcontaining a polar group with the polymer containing a cyclic structurein the presence of a peroxide. The type of the reaction may be to addthe polymer containing a cyclic structure, the unsaturated compoundcontaining a polar group, and the peroxide all together to the mixedsolvent of the nonpolar organic solvent and polar organic solvent or todissolve the polymer containing a cyclic structure and unsaturatedcompound containing a polar group in the mixed solvent and in that stateadding the peroxide continuously or intermittently to cause thereaction.

[0059] The second method of obtaining the graft polymer containing acyclic structure of the present invention is to dissolve the polymercontaining a cyclic structure in an organic solvent and gradually addthe unsaturated compound containing a polar group and peroxidecontinuously or intermittently to cause a graft reaction. In the secondmethod of production, the organic solvent for dissolving the polymercontaining a cyclic structure may be either a nonpolar organic solventor polar organic solvent, but a mixed solvent of these is preferable.The unsaturated compound containing a polar group and peroxide may beadded separately or mixed. The unsaturated compound containing a polargroup or peroxide may be added dissolved in an organic solvent. Thefirst method of production and the second method of production have theadvantages of small coloring of the graft polymer containing a cyclicstructure obtained, little agglomeration, and a narrow distribution ofmolecular weight, but the second method of production is preferable inthat it is more superior in these.

[0060] The nonpolar organic solvent is not particularly limited so longas it can dissolve a polymer containing a cyclic structure. For example,toluene, xylene, ethylbenzene, t-butylbenzene, and other aromatichydrocarbons; n-pentane, hexane, heptane, and other aliphatichydrocarbons; cyclopentane, cyclohexane, and other alicyclichydrocarbons, etc. may be mentioned. Aromatic hydrocarbons or alicyclichydrocarbons are particularly preferable. These nonpolar organicsolvents may be used alone or in combinations of two or more types.

[0061] The polar organic solvent is not particularly limited, but apolar organic solvent not having active hydrogen is usually used. As apolar organic solvent not having active hydrogen, chlorobenzene,dichlorobenzene, trichlorobenzene, and other halogenated hydrocarbons;acetone, methylethylketone, methyisobutylketone, cyclohexanone,benzophenone, and other ketones; diethylether, tetrahydrofuran, anisole,and other ethers; N-methylpyrrolidone, N-ethylpyrrolidone,N-phenylpyrrolidone, N-benzylpyrrolidone, N,N-dimethylformamide, andother amide compounds; methyl formate, ethyl formate, methyl acetate,ethyl acetate, propyl acetate, methyl propionate, ethyl propionate,propyl propionate, methyl butyrate, ethyl butyrate, ethyl lactate,dimethyl carbonate, dimethyl phthalate, diethyl phthalate, γ-butyllactone, and other esters; acetonitrile, propionitrile, butyronitrile,benzonitrile, captonitrile, and other nitrile compounds; dimethylsulfoxide and other sulfoxide compounds, etc. may be mentioned. Amongtheses, ketones, ethers, esters, etc. are preferable. These polarorganic solvents may be used alone or in combinations of two or moretypes. The polar organic solvent may be mixed with the hydrocarbon-basedsolvent at the initial stage of the graft reaction or added during themiddle of the reaction. If a nonpolar organic solvent and polar organicsolvent are used together as the solvent for the graft reaction, thegraft ratio can be raised and the gel content of the polymer can bereduced.

[0062] The ratio of the nonpolar organic solvent and polar organicsolvent in the mixed solvent is suitably selected according to the typeof the solvents, but in terms of the weight ratio of the polar organicsolvent to the nonpolar organic solvent, normally is 95:5 to 5:95,preferably 90:10 to 15:85, more preferably 85:15 to 30:70, mostpreferably 85:15 to 40:60. When the ratio of the nonpolar organicsolvent and polar organic solvent is in this range, a graft polymerhaving a high graft ratio and low gel content or low Ha/La ratio iseasily obtained and suitable. The Ha/La ratio is sufficiently in thisrange at the time of end of the graft reaction. It is also possible touse only the nonpolar organic solvent before the start of the reactionand increase the polar organic solvent along with the trends in thegraft reaction to obtain the above ratio range.

[0063] The amount of the mixed solvent used is suitably selected inaccordance with the reaction conditions etc., but, with respect to 100parts by weight of the polymer containing a cyclic structure, isnormally 50 to 5,000 parts by weight, preferably 70 to 3,000 parts byweight, more preferably 100 to 1,000 parts by weight.

[0064] The peroxide is not particularly limited. Specifically, benzoylperoxide, dichlorobenzoyl peroxide, dicumyl peroxide, di-tert-butylperoxide, 2,5-dimethyl-2,5-di(peroxidebenzoate)hexyl-3,1,4-bis(tert-butylperoxyisopropyl)benzene, lauroyl peroxide,tert-butylperacetate, tert-butylperisobutyrate,tert-butylper-sec-octoate, tert-butylperpivalate, cumylperpivalate,tert-butylperdiethyl acetate, etc. may be mentioned.

[0065] These peroxides may be used alone or in combinations of two ormore types. The amount of the peroxide used may be suitably selected inaccordance with the graft ratio and reaction conditions etc., but, withrespect to 100 parts by weight of the unsaturated organic compound, isnormally 1 to 50 parts by weight, preferably 1.5 to 40 parts by weight,more preferably 2 to 30 parts by weight. If the amount of use of theperoxide is excessively small, the graft ratio will not rise.Conversely, if excessively small, gelation progresses. Neither ispreferable.

[0066] The method of addition of the peroxide or unsaturated compoundcontaining a polar group to the reaction system is not particularlylimited. It may be added all together or gradually added by intermittentor continuous addition. The amount of gradual addition of the peroxideor unsaturated compound containing a polar group is normally at least{fraction (1/2)} of the total amount, preferably at least {fraction(2/3)}, more preferably at least {fraction (3/4)}. If the amount ofgradual addition becomes greater, the high molecular weight/lowmolecular weight area ratio of the graft polymer becomes smaller (highmolecular weight ingredients become smaller) and the filterability ofthe solution or the flatness, smoothness, buriability, etc. of thecoating film become more superior, so this is preferable.

[0067] The reaction temperature of the graft modification is normally 0to 400° C., preferably 30 to 350° C., more preferably 60 to 200° C.,while the reaction temperature is normally 1 minute to 24 hours,preferably 30 minutes to 10 hours. After the end of the graft reaction,it is possible to separate the graft polymer containing a cyclicstructure by an ordinary method. For example, it is possible to obtainit by adding drop-wise the reaction solution to a poor solvent to causeprecipitation of the graft polymer containing a cyclic structure.

[0068] Curable Composition

[0069] The curable composition of the present invention contains theabove graft polymer containing a cyclic structure and curing agent asessential ingredients and, if necessary, a curing accelerator, curingaid, and other ingredients.

[0070] The curing agent is not particularly limited so long as it is onewhich cures a graft polymer containing a cyclic structure. For example,an ionic curing agent, radical curing agent, etc. may be used. An ioniccuring agent is preferable from the viewpoint of the insulationresistance, heat resistance, surface hardness, and affinity with a graftpolymer containing a cyclic structure.

[0071] As an ionic curing agent, hexamethylene diamine, triethylenetetramine, diethylene triamine, tetraethylene pentamine,diaminocyclohexane,3(4),8(9)-bis(aminomethyl)tricyclo[5,2,1,0^(2,6)]decane,1,3-(diaminomethyl)cyclohexane, menthene diamine, isophorone diamine,N-aminoethylpiperadine, and other polyamine compounds;4,4′-bisazidobenzal(4-methyl)cyclohexanone, 4,4′-diazidocalcone, andother bisazide compounds; phthalic anhydride, pyromellitic anhydride,benzophenone tetracarboxylic anhydride, nadic anhydride, and other acidanhydrides; fumaric acid, phthalic acid, maleic acid, and otherpolyhydric carboxylic acids; 1,3-butanediol, 1,4-butanediol,1,1,1-trimethylolpropane, and other polyol compounds; phenol novolakresin, cresol novolak resin, and other polyhydric phenol compounds;nylon-6, nylon-66, polyhexamethylene diamine terephthalamide, and otherpolyamide compounds; hexamethylene diisocyanate, toluidienediisocyanate, and other diisocyanate compounds; phenol novolak typeepoxy compounds, cresol novolak type epoxy compounds, bisphenol A typeepoxy compounds, bisphenol F type epoxy compounds, brominated bisphenolA type epoxy compounds, dicyclopentadiene type epoxy resins, and otherpolyhydric epoxy compounds, etc. may be mentioned. Among these, from theviewpoint of superiority in low dielectric property, low waterabsorption, heat resistance, and affinity with a graft polymercontaining: a cyclic structure, a polyol compound, polyhydric phenolcompound, polyhydric epoxy compound, etc. are preferable. In particular,a polyhydric epoxy compound is preferable.

[0072] As a radical curing agent, methylethylketone peroxide,cyclohexanone peroxide, 1,1-bis(t-butylperoxy)3,3,5-tricyclohexane,2,2-bis(t-butylperoxy)butane, t-butyl hydroperoxide, octanoyl peroxide,isobutyryl peroxide, peroxydicarbonate, and other organic peroxides etc.may be mentioned.

[0073] These curing agents may be used alone or as combinations of twoor more types. The amount of the curing agent blended is, with respectto 100 parts by weight of the graft polymer containing a cyclicstructure, normally 5 to 150 parts by weight, preferably 15 to 120 partsby weight, more preferably 30 to 100 parts by weight.

[0074] In the present invention, to further raise the curability of thegraft polymer containing a cyclic structure, it is possible to use acuring accelerator or curing aid.

[0075] The curing accelerator is not particularly limited. When thecuring agent is for example a polyhydric epoxy compound, a tertiaryamine-based compound, boron trifluoride complex, etc. is preferable.Among these, if using a tertiary amine-based compound, the laminabilitywith micro-interconnections, insulation resistance, heat resistance, andchemical resistance are improved.

[0076] As a specific example of a tertiary amine-based compound,benzyldimethylamine, triethanolamine, triethylamine, and otherchain-like tertiary amine compounds; pyrazoles, pyridines, pyradines,pyrimidines, indazoles, quinolines, isoquinolines, imidazoles,triazoles, and other compounds may be mentioned. Among these,imidazoles, in particular substituted imidazole compounds havingsubstituent groups are preferred.

[0077] As specific examples of substituted imidazole compounds,2-ethylimidazole, 2-ethyl-4-methylimidazole,bis-2-ethyl-4-methylimidazole, and other alkyl-substituted imidazolecompounds; 2-phenylimidazole, 2-phenyl-4-methylimidazole,1-benzyl-2-methylimidazole, 2-benzyl-2-phenylimidazole, benzimidazole,and other imidazole compounds substituted by aryl groups or arakylgroups or other hydrocarbon groups having cyclic structures, etc. may bementioned. Among these, imidazoles having substituent groups containingcyclic structures, in particular 1-benzyl-2-phenylimidazole, arepreferable from the viewpoint of affinity with a graft polymercontaining a cyclic structure.

[0078] These curing accelerators can be used alone or in combinations oftwo or more types. The amount of the curing accelerator blended issuitably selected in accordance with the objective of use, but is, withrespect to 100 parts by weight of the graft polymer containing a cyclicstructure, normally 0.001 to 30 parts by weight, preferably 0.01 to 10parts by weight, more preferably 0.03 to 5 parts by weight.

[0079] The curing aid is not particularly limited. Quinone dioxime,benzoquinone dioxime, p-nitrosophenol, and other oxime-nitroso-basedcuring agents; N,N-m-phenylene bismaleimide and other maleimide-basedcuring aids; diallyl phthalate, triallyl cyanulate, triallylisocyanulate, and other allyl-based curing agents; ethyleneglycoldimethacrylate, trimethylolpropane trimethacrylate, and othermethacrylate-based curing aids; vinyltoluene, ethylvinylbenzene,divinylbenzene, and other vinyl-based curing aids etc. may be mentioned.

[0080] These curing aids may be used alone or in combinations of two ormore types. The amount blended is, with respect to 100 parts by weightof the curing agent, normally 1 to 1000 parts by weight, preferably 10to 500 parts by weight.

[0081] The curable composition of the present invention may further haveblended into it other ingredients as desired in addition to the abovegraft polymer containing a cyclic structure and curing agent (includingcuring accelerator and curing aid). As the other ingredients, forexample, other polymers or other compounding agents etc. may bementioned.

[0082] As the other polymer, for example, natural rubber, polybutadienerubber, polyisoprene rubber, acrylonitrile-butadiene copolymer rubber,hydrogenated acrylonitrile-butadiene copolymer rubber,ethylene-propylene-styrene block copolymer rubber, urethane-basedthermoplastic elastomers, and other rubbery polymers or low densitypolyethylene, high density polyethylene, polypropylene, nylon 66,ethylene-vinyl acetate copolymer, polyester, polycarbonate, and otherpolymers not having cyclic structures, that is, resins, may bementioned.

[0083] These other polymers may be used alone or in combinations of twoor more types. The amount of the other polymers blended is, with respectto 100 parts by weight of the graft polymer containing a cyclicstructure, normally not more than 100 parts by weight, preferably notmore than 70 parts by weight, more preferably not more than 50 parts byweight. The lower limit is 0 part by weight.

[0084] As other compounding agents, for example, thiol compounds andother bondability improving agents, fillers, flame retardants, heatresistance stabilizers, weather resistance stabilizers, leveling agents,anti-static agents, slip agents, antiblocking agents, anti-foggingagents, lubricants, dyes, pigments, natural oils, synthetic oils,varnishes, emulsifiers, etc. may be mentioned. These compounding agentsare suitably selected in a range not impairing the object of the presentinvention.

[0085] A typical form of the curable composition of the presentinvention is a varnish comprised of the curable composition dissolved inan organic solvent.

[0086] As specific examples of organic solvents used in preparation of avarnish, as nonpolar solvents, toluene, xylene, ethylbenzene,trimethylbenzene, and other aromatic hydrocarbons; n-pentane, n-hexane,n-heptane, and other aliphatic hydrocarbons; cyclopentane, cyclohexane,and other alicyclic hydrocarbons; etc. may be mentioned. As polarsolvents, chlorobenzene, dichlorobenzene, trichlorobenzene, and otherhalogenated hydrocarbons; methylethylketone, methylisobutylketone,cyclopentanone, cyclohexanone, acetophenone, and other ketone-basedsolvents; cyclohexyl acetate, methyl benzoate, ethyl benzoate, γ-butyllactone, propyleneglycol methylether acetate, ethyleneglycol methyletheracetate, and other ester-based solvents; tetrahydrofuran,tetrahydropyrane, anisole, and other ether-based solvents; ethylenecarbonate, propylene carbonate, and other carbonate-based solvents;dimethyl formamide, dimethyl acetoamide, N-methylpyrrolidone, and otheramide-bsaed solvents may be mentioned.

[0087] These solvents may be used alone or in combinations of two ormore types. Among these solvents, a mixed solvent of a nonpolar solventsuch as aromatic hydrocarbon-based solvent or alicyclichydrocarbon-based solvent and a polar solvent such as a ketone-basedsolvent is preferable as the solution comprising the dissolved graftpolymer containing a cyclic structure of the present invention, curingagent, etc. is superior in ability to bury micro-interconnections andwill not cause bubbles etc. The ratio of mixing of these nonpolarorganic solvents and polar organic solvents may be suitably selected,but by weight ratio is normally 5:95 to 95:5, preferably 10:90 to 90:10,more preferably 20:80 to 80:20.

[0088] The amount of the organic solvent used is suitably selected inaccordance with the objective of use, but the solid contentconcentration is normally 5 to 80 wt %, preferably 10 to 70 wt %, morepreferably 20 to 60 wt %.

[0089] The method of dispersion or dissolution of the ingredients of thecurable composition in the organic solvent may be an ordinary method.For example, it may be performed by stirring using a stirrer andmagnetic stirrer, a method using a high speed homogenizer, disperser,planetary stirring machine, twin-screw stirring machine, ball mill,triple roll, etc.

[0090] Shaped Article

[0091] As the shaped article obtained using the curable composition ofthe present invention, a film or sheet can be preferably formed by usingan ordinary solution casting method to for example coat the abovevarnish on a support, then dry off the solvent. As the coating method,any method such as dip coating, roll coating, curtain coating, diecoating, and slit coating can be used. The conditions for removing thesolvent and drying are suitably selected according to the type of thesolvent. The drying temperature is usually 20 to 300° C., preferably 30to 200° C., while the drying time is usually 30 seconds to 1 hour,preferably 1 minute to 30 minutes.

[0092] The thickness of the film or sheet is normally 0.1 to 150 μm,preferably 0.5 to 100 μm, more preferably 1.0 to 80 μm.

[0093] As the support, a resin film, metal foil, etc. may be mentioned.As a resin film, normally a thermoplastic resin film is used.Specifically, a polyester film, polypropylene film, polyethylene film,polycarbonate film, polyethylene naphthalate film, polyarylate film,nylon film, etc. may be mentioned. Among these resin films, apolyethylene terephthalate film, polyethylene naphthalate film, or otherpolyester film is preferable from the viewpoint of the heat resistance,chemical resistance, peelability after lamination, etc. As the metalfoil, for example a copper foil, aluminum foil, nickel foil, chromefoil, gold foil, silver foil, etc. may be mentioned. The thickness ofthe support is not particularly limited, but from the viewpoint of workefficiency etc., normally is 1 μm to 150 μm, preferably 2 μm to 100 μm,more preferably 3 to 50 μm.

[0094] The relative dielectric constant (e) of the shaped articleobtained using the curable composition of the present invention issuitably selected according to the objective of use, but in terms ofvalue measured at 1 MHz according to JIS C 6481 is normally not morethan 4, preferably not more than 3, more preferably not more than 2.85,most preferably not more than 2.7.

[0095] The water absorption of the shaped article obtained using thecurable composition of the present invention is suitably selected inaccordance with the objective of use, but in terms of value measured inaccordance with JIS C 6481 is normally not more than 0.5%, preferablynot more than 0.2%, more preferably not more than 0.15%, most preferablynot more than 0.1%.

[0096] Applications

[0097] The curable composition of the present invention is, as avarnish, superior in filterability, superior in smoothness, flatness,buriability, surface hardness, etc., and further superior in lowdielectric property, low water absorption, and heat resistance, so issuitable for various organic materials for electronic parts and can beused in the form of a varnish, film, or sheet for example for aninsulating material for a printed writing board, an insulating materialfilm between layers for buildup multilayer boards, an insulatingmaterial film of a flexible printed writing board, an interlayerinsulating material film for LSI's, VLSI's, and other semiconductordevices, and other insulating materials; a cover coating material for asemiconductor device, a protective coating material, a solder resistmaterial for a printed writing board, etc. Further, the curablecomposition of the present invention is superior in transparency aswell, so can be used for the material of a color filter for a liquidcrystal display substrate, a flattening film for a TFT array, aflattening film for various interconnections, cells for liquid crystaldisplays (also called “polymer cells”), etc.

[0098] Next, the present invention will be explained more specificallyby giving examples and comparative examples. In these examples, “parts”and “%” are based on weight unless otherwise indicated.

[0099] The following methods were used for the various tests andevaluation:

[0100] (1) Molecular Weight

[0101] The weight average molecular weight (Mw) and number averagemolecular weight (Mn) of a sample polymer were measured as standardpolystyrene converted values by GPC using THF as a development solutionby charging a 1 μl sample of a 0.5% THF solution in columns made by Toso(TSKgel G4000, TSKgel G5000 connected in series).

[0102] (2) Gel Content

[0103] A 10% THF solution of the sample polymer was filtered by a Teflonfilter having a pore size of 0.22 μm, then the undissolved polymerremaining on the filter was recovered, vacuum dried at a temperature of120° C. for 12 hours, and measured for weight to find the ratio with theweight of the sample polymer before filtration (%)

[0104] (3) Hydrogenation Rate and Graft Ratio

[0105] The hydrogenation rate of the main chain of the polymercontaining a cyclic structure (norbornene-based ring-opening polymer)and the graft ratio of the polymer containing a cyclic structure weremeasured by ¹H-NMR.

[0106] (4) Filterability

[0107] 10 g of the sample polymer was used to obtain a 10% THF solutionwhich was then filtered using a filter having a pore size of 0.22 μm andan area of 20 cm² at a pressure of 2 kg/cm². The time (Tf) required forfiltering the entire amount was measured and evaluated by the followingcriteria:

[0108] VG (Very Good): TF≦60 seconds

[0109] G (Good): 60 seconds<Tf≦120 sections

[0110] F (Fair): 120 seconds<Tf≦180 seconds

[0111] P (Poor): 180 seconds<Tf

[0112] (5) Smoothness

[0113] The sample polymer was dissolved in the formulation shown in theexamples to obtain a 30% trimethylbenzene/cyclohexane (70%/30%) solutionwhich was then spin coated on a silicon substrate under conditions of aspeed of 1000 rpm for 30 seconds. The substrate was prebaked at 80° C.for 10 minutes, then hard baked at 230° C. for 1 hour. The evenness ofthe surface at this time was observed under an electron microscope andevaluated by the following criteria:

[0114] VG: No undulation at all

[0115] G: Slight undulation at end surface of substrate

[0116] F: Slight undulation on entire surface of substrate

[0117] P: Locations with large undulation

[0118] (6) Flatness

[0119] A solution prepared in the same way as in the above (5) wascoated on a silicon oxide film substrate having step differences of aline width of 10 μm and height of 1.0 μm, then prebaked and hard bakedto form a coating film over the step differences. The maximum stepdifference of the coating film was measured using a contact-type filmthickness measuring device, then the flatness (d) of the followingformula was calculated and evaluated by the following criteria:

d=Maximum step difference÷Initial step difference(1.0 μm)×100(%)

[0120] G: d≦5%

[0121] F: 5%<ds≦10%

[0122] P: 10%<d

[0123] (7) Low Dielectric Property

[0124] The dielectric constant (∈) was measured in accordance with JIS C6481 and evaluated by the following criteria:

[0125] VG: ∈≦2.70

[0126] G: 2.70<∈≦2.85

[0127] F: 2.85<∈≦3.00

[0128] P: 3.00<∈

[0129] (8) Low Water Absorption

[0130] The water absorption rate (w) was measured in accordance with JISC 6481 and evaluated by the following criteria:

[0131] VG: w≦0.10%

[0132] G: 0.10%<w≦0.15%

[0133] F: 0.15%<w≦0.20%

[0134] P: 0.20<w

[0135] (9) Surface Hardness

[0136] The curable composition was coated on a glass sheet, then curedat 230° C. for 1 hour to obtain a coating film of a thickness of 1 μm.This was pressed by a trigonal pyramid indenter (115°) at a load speedof 0.0145 gf/S using a dynamic ultrafine hardness meter (DUH-201, madeby Shimadzu Corporation). The pressed depth (h) giving a load of 0.5mN(P) was measured. The DHT115 of the following formula was calculatedfrom the results and evaluated by the following criteria:

DHT115=3.838 P/h ²

[0137] VG: DHT115≧55

[0138] G: 55>DHT115≧50

[0139] F: 50>DUH115≧45

[0140] P: 45>DUH115

[0141] (10) Heat Resistance

[0142] The curable composition was coated on a glass sheet, then curedat 230° C. for 1 hour to obtain a 2 μm coating film. Indium tin oxide(ITO) was vapor deposited over this, then the appearance of the ITO filmwas observed and evaluated by the following criteria. Note that theconditions for forming the ITO film were an electrodischarge voltage of60V, a film thickness of 1000 Å, and a glass sheet temperature of 220 to240° C.

[0143] VG: No wrinkling in appearance

[0144] G: Slight wrinkling at one end of glass sheet

[0145] F: Wrinkling at four ends of glass sheet

[0146] P: Wrinkling over entire surface

[0147] (11) Molecular Weight/Area Ratio

[0148] Ratio of high molecular weight side area Ha and low molecularweight side area La divided by a vertical line suspended from a peak topof a differentiated elution profile measured by GPC in the above (1) toa baseline for the graft polymer containing a cyclic structure.

[0149] (12) Interconnection Buriability

[0150] The curable composition was dissolved in a1,2,4-trimethylbenzene/cyclohexanone/tertiary butyl acetate (weightratio 6/3.5/0.5) solution to a solid content concentration of 30 wt %.This solution was coated on a Teflon plate of a thickness of 3 mm by thedoctor blade method, then dried at a temperature of 120° C. for 5minutes to obtain a semicured film of a thickness of 50 μm. The obtainedfilm was pressed on an FR-4 grid board having copper interconnections ofa step difference of 35 μm and line width of 50 μm arranged at lineintervals of 50 μm under vacuum at a temperature of 200° C. for 1 hour.The obtained grid board was cut in a direction perpendicular to theinterconnections and the cross-section was observed under an electronmicroscope and evaluated by the following criteria.

[0151] VG: Completely buried, resin surface smooth

[0152] G: Completely buried, but slight undulation at surface

[0153] F: Burying insufficient, slight voids

[0154] P: Burying insufficient, numerous voids

EXAMPLE 1

[0155] Preparation of Graft Polymer A Containing a Cyclic Structure

[0156] Using a polymerization catalyst comprised of tungstenhexachloride, triisobutyl aluminum, and isobutyl alcohol,8-ethyltetracyclo[4,4,0,1^(2,5),1^(7,10)]-dod eca-3-ene (hereinafterreferred to as “ETD”) was polymerized by a known method, thenhydrogenated using a hydrogenation catalyst comprised of nickel acetylacetate and triisobutyl aluminum to obtain a hydrogenatednorbornene-based ring-opening polymer (hereinafter referred to as the“polymer A”) (hydrogenation rate: at least 99%). Next, 100 parts of thepolymer A, 200 parts of maleic anhydride, 150 parts of t-butyl benzene,and 150 parts of ethyl benzoate were mixed in an autoclave. After thesewere completely dissolved, the atmosphere was replaced with nitrogen,then the temperature raised to 135° C. 20 parts of dicumyl peroxide weredivided into 10 sections in the autoclave and the sections added at 12minute intervals over 2 hours, then the mixture was allowed to react for3 hours. The dicumyl peroxide remaining in the reaction solution(undissolved part) was assayed by gas chromatography, whereupon it wasconfirmed to be not more than 2%. The reaction solution was addeddrop-wise into isopropanol and solidified and dried to obtain the graftpolymer containing a cyclic structure A. The properties of the graftpolymer A containing a cyclic structure are shown in Table 1.

EXAMPLE 2

[0157] Preparation of Graft Polymer B Containing a Cyclic Structure

[0158] The same procedure was performed as in Example 1 except forchanging the amount of the dicumyl peroxide to 15 parts and the amountof the maleic anhydride to 150 parts to obtain the graft polymer Bcontaining a cyclic structure. The properties of the graft polymer Bcontaining a cyclic structure are shown in Table 1.

EXAMPLE 3

[0159] Preparation of Graft Polymer C Containing a Cyclic Structure

[0160] The same procedure was performed as in Example 1 except forchanging the amount of the dicumyl peroxide to 10 parts and the amountof the maleic anhydride to 100 parts to obtain the graft polymer Ccontaining a cyclic structure. The properties of the graft polymer Ccontaining a cyclic structure are shown in Table 1.

EXAMPLE 4

[0161] Preparation of Graft Polymer D Containing a Cyclic Structure

[0162] The same procedure was performed as in Example 1 except forchanging the amount of the dicumyl peroxide to 7 parts and the amount ofthe maleic anhydride to 70 parts and changing the methyl benzoate toanisole to obtain the graft polymer D containing a cyclic structure. Theproperties of the graft polymer D containing a cyclic structure areshown in Table 1.

EXAMPLE 5

[0163] Preparation of Graft Polymer E Containing a Cyclic Structure

[0164] The same procedure was performed as in Example 1 except forchanging the amount of the dicumyl peroxide to 7 parts, the amount ofthe maleic anhydride to 70 parts, and the amount of the tertiary butylbenzene to 200 parts and changing the 150 parts of ethyl benzoate to 100parts of anisole to obtain the graft polymer E containing a cyclicstructure. The properties of the graft polymer E containing a cyclicstructure are shown in Table 1.

EXAMPLE 6

[0165] Preparation of Graft Polymer F Containing a Cyclic Structure

[0166] The same procedure was performed as in Example 1 except forchanging the amount of the dicumyl peroxide to 7 parts, the amount ofthe maleic anhydride to 70 parts, and the amount of the tertiary butylbenzene to 250 parts and changing the 150 parts of ethyl benzoate to 50parts of anisole to obtain the graft polymer F containing a cyclicstructure. The properties of the graft polymer F containing a cyclicstructure are shown in Table 1.

EXAMPLE 7

[0167] Preparation of Graft Polymer G Containing a Cyclic Structure

[0168] The same procedure was performed as in Example 1 except forchanging the amount of the dicumyl peroxide to 5 parts and the amount ofthe maleic anhydride to 50 parts and changing the ethyl benzoate toanisole to obtain the graft polymer G containing a cyclic structure. Theproperties of the graft polymer G containing a cyclic structure areshown in Table 1.

COMPARATIVE EXAMPLE 1

[0169] Preparation of Graft Polymer H Containing a Cyclic Structure

[0170] The same procedure was performed as in Example 1 except forchanging the amount of the dicumyl peroxide to 3.5 parts, the amount ofthe maleic anhydride to 35 parts, and the amount of the tertiary butylbenzene to 300 parts and not using ethyl benzoate to obtain the graftpolymer H containing a cyclic structure. The properties of the graftpolymer H containing a cyclic structure are shown in Table 1.

COMPARATIVE EXAMPLE 2

[0171] Preparation of Graft Polymer I Containing a Cyclic Structure

[0172] The same procedure was performed as in Example 1 except forchanging the amount of the dicumyl peroxide to 5.0 parts, the amount ofthe maleic anhydride to 50 parts, and the amount of the tertiary butylbenzene to 300 parts and not using ethyl benzoate to obtain the graftpolymer I containing a cyclic structure. The properties of the graftpolymer I containing a cyclic structure are shown in Table 1. Further,the graft polymer I containing a cyclic structure was dissolved in THFto obtain a 10 wt % solution which was then attempted to be filteredusing a filter having a pore size of 0.22 μm and area of 20 cm² at apressure of 2 kg/cm².

[0173] (Rest of page blank) TABLE 1 Graft Weight polymer averageMolecular containing molecular Gel weight area cyclic Graft ratio weightcontent ratio No. structure (mol %) (×10⁴) (wt %) Ha/La Example 1 A 974.53 0.008 1.30 Example 2 B 78 4.22 0.006 1.25 Example 3 C 60 4.34 0.0071.23 Example 4 D 45 4.20 0.004 1.16 Example 5 E 45 4.61 0.03 1.23Example 6 F 45 4.78 0.08 1.34 Example 7 G 35 4.44 0.002 1.16 Comp. Ex. 1H 25 5.95 0.26 1.87 Comp. Ex. 2 I 35 6.89 Large 1.91

[0174] As shown in Table 1, by using jointly a nonpolar organic solventand a polar organic solvent as the reaction solvent, a high modificationof a graft ratio of at least 35 mol % is performed and the obtainedgraft polymer containing a cyclic structure has a weight averagemolecular weight of 1,000 to 1,000,000, a gel content of not more than0.1%, a low amount, or an Ha/La of not more than 1.6 (Examples 1 to 7).Comparative Examples 1 and 2 using only a nonpolar organic solvent asthe reaction solvent had remarkably increased gel contents andremarkably increased Ha/La ratios.

EXAMPLES 8 TO 14 AND COMPARATIVE EXAMPLES 3 AND 4

[0175] Films obtained by preparing, casting, and drying a curablecomposition by mixing the graft polymer containing a cyclic structureobtained in Examples 1 to 7 and Comparative Examples 1 and 2, apolyhydric epoxy compound, a dicyclopentadiene-type epoxy resin (made byNippon Kayaku, XD-1000-2L), and 1-benzyl-2-phenylimidazole in the partsof formulation shown in Table 2 were evaluated for filterability,smoothness, flatness, low dielectric property, low water absorption, andheat resistance. The results are shown in Table 2. In the table, adicyclopentadiene-type epoxy resin is indicated by “XD” and1-benzyl-2-phenylimidazole is indicated by “BPZ”.

[0176] (Rest of page blank) TABLE 2 Graft polymer containing a Curingcyclic Curing acceler- Low Intercon- structure agent ator Low di- waterSurface Heat nection (parts by (parts by (parts by Filter- Smooth- Flat-electric absorp- hard- resist- buri- No. weight) weight) weight) abilityness ness property tion ness ance ability Ex.8 A (100) XD (40) BPZ VG VGVG VG VG VG VG VG (0.5) Ex.9 B (100) XD (40) BPZ VG VG VG VG VG VG VG VG(0.5) Ex.10 C (100) XD (40) BPZ VG VG VG VG VG VG VG VG (0.5) Ex.11 D(100) XD (40) BPZ VG VG VG VG VG VG VG VG (0.5) Ex.12 E (100) XD (40)BFZ VG G G VG VG VG VG VG (0.5) Ex.13 F (100) XD (40) BPZ VG F F VG VGVG VG VG (0.5) Ex.14 G (100) XD (40) BPZ VG VG VG VG VG G G VG (0.5)Comp. H (100) XD (40) BPZ F P P VG VG P P P Ex. 3 (0.5) Comp. I (100) XD(40) BPZ P P P VG VG G G P Ex. 4 (0.5)

[0177] As shown in Table 2, each of the curable compositions of thepresent invention is superior in all evaluation items (Examples 8 to14).

[0178] However, Comparative Example 3 and Comparative Example 4 usinggraft polymers containing cyclic structures with low graft ratios andlarge gel contents failed to give superior results in items other thanlow dielectric property and low water absorption.

1. A graft polymer containing a cyclic structure comprised of a polymer containing a cyclic structure graft-modified with an unsaturated compound containing a polar group, having a graft ratio of 10 mol % to 150 mol %, having a gel content of not more than 0.1 wt %, and having a weight average molecular weight of 1,000 to 1,000,000.
 2. A graft polymer containing a cyclic structure comprised of a polymer containing a cyclic structure graft-modified with an unsaturated compound containing a polar group, having a graft ratio of 10 mol % to 150 mol %, having a ratio (Ha/La) of high molecular weight side area (Ha) and low molecular weight side area (La) divided by a vertical line suspended from a peak top of a differentiated elution profile measured by gel permeation chromatography to a baseline of not more than 1.6, and having a weight average molecular weight of 1,000 to 1,000,000.
 3. The graft polymer containing a cyclic structure as set forth in claim 1 or 2, wherein the polymer containing a cyclic structure is a norbornene-based polymer or its hydride.
 4. The graft polymer containing a cyclic structure as set forth in claim 1 or 2, wherein the unsaturated compound containing a polar group is an unsaturated carboxylic anhydride compound.
 5. The graft polymer containing a cyclic structure as set forth in claim 1 or 2, wherein the graft ratio is 30 mol % to 120 mol %.
 6. The graft polymer containing a cyclic structure as set forth in claim 1 or 2, wherein the weight average molecular weight is 5,000 to 500,000.
 7. The graft polymer containing a cyclic structure as set forth in claim 1, wherein the gel content is not more than 0.05 wt %.
 8. The graft polymer containing a cyclic structure as set forth in claim 2, wherein the ratio (Ha/La) is not more than 1.4.
 9. A method of production of a graft polymer containing a cyclic structure comprising dissolving a polymer containing a cyclic structure and unsaturated compound containing a polar group in a mixed solvent of a nonpolar organic solvent and a polar organic solvent and in that state causing a graft reaction of the unsaturated compound containing a polar group with the polymer containing a cyclic structure in the presence of a peroxide.
 10. A method of production of a graft polymer containing a cyclic structure comprising dissolving a polymer containing a cyclic structure and unsaturated compound containing a polar group in a mixed solvent of a nonpolar organic solvent and a polar organic solvent and in that state causing a graft reaction of the unsaturated compound containing a polar group while continuously or intermittently adding a peroxide.
 11. A method of production of a graft polymer containing a cyclic structure comprising dissolving a polymer containing a cyclic structure in an organic solvent and in that state causing a graft reaction of an unsaturated compound containing a polar group with the polymer containing a cyclic structure while continuously or intermittently adding a peroxide and the unsaturated compound containing a polar group.
 12. The method of production of a graft polymer containing a cyclic structure as set forth in claim 11, wherein the organic solvent is a mixed solvent of a nonpolar organic solvent and a polar organic solvent.
 13. The method of production of a graft polymer containing a cyclic structure as set forth in claim 9, 10, or 12, wherein the mixing ratio of the nonpolar organic solvent and the polar organic solvent is 95:5 to 5:95.
 14. The method of production of a graft polymer containing a cyclic structure as set forth in any one of claims 9 to 11, wherein the polymer containing a cyclic structure is a norbornene-based polymer or its hydride.
 15. The method of production of a graft polymer containing a cyclic structure as set forth in any one of claims 9 to 11, wherein the unsaturated compound containing a polar group is an unsaturated carboxylic anhydride compound.
 16. A curable composition containing a graft polymer containing a cyclic structure and a curing agent, wherein said graft polymer containing a cyclic structure is comprised of a polymer containing a cyclic structure graft-modified with an unsaturated compound containing a polar group, having a graft ratio of 10 mol % to 150 mol %, having a gel content of not more than 0.1 wt %, and having a weight average molecular weight of 1,000 to 1,000,000.
 17. A curable composition containing a graft polymer containing a cyclic structure and a curing agent, wherein said graft polymer containing a cyclic structure is comprised of a polymer containing a cyclic structure graft-modified with an unsaturated compound containing a polar group, having a graft ratio of 10 mol % to 150 mol %, having a ratio (Ha/La) of high molecular weight side area (Ha) and low molecular weight side area (La) divided by a vertical line suspended from a peak top of a differentiated elution profile measured by gel permeation chromatography to a baseline of not more than 1.6, and having a weight average molecular weight of 1,000 to 1,000,000. 